Fluorinated 1,3-Dioxolane Compounds, Fluorinated Polymers of the Compounds, and Optical or Electrical Materials Comprising the Polymers

ABSTRACT

A production method of fluorinated compounds, for producing a compound represented by formula (3) in a fluorine-based solution in a flow of fluorine gas after reaction of at least one type of compounds represented by formula (1) and at least one type of compounds represented by formula (2). Similarly, fluorinated compounds represented by formula (4) prepared by the fluorination of compounds obtained by the reaction of formula (1) and formula (2)′. The fluorinated polymers obtained by the polymerizations of formula (3) and (4) compounds are useful as an optical or electrical materials. 
     
       
         
         
             
             
         
       
     
     wherein R 1 , R 2 , R 3 , R 4 , R ff   1 , R ff   2 , R ff   3 , R ff   4 , X, Y, Z, and n are defined in the specification respectively.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a division of co-pending U.S. patent application Ser. No.10/570,210, which is the U.S. national phase of InternationalApplication No. PCT/JP2004/012866 filed Aug. 30, 2004, which claims thebenefit of U.S. patent application Ser. No. 60/498,689 filed Aug. 29,2003, and Japanese patent application No. 2004-177125 filed Jun. 15,2004, the disclosures of all of which are hereby incorporated byreference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a method for fluorinated compounds,fluorinated compounds produced by the method, fluorinated polymersobtained from the fluorinated compounds, and optical or electricalmaterials using the fluorinated polymers.

2. Brief Description of Related Technology

Fluorinated polymers are useful materials that are used in variousapplications, for example, plastic optical fibers and photoresistmaterials, or surface modifiers. However, the synthetic processes offluorinated polymers are complicated and costly.

A fluorinated polymer is obtained by polymerization of a fluorinatedcompound having a polymeric unsaturated group. As an example offluorinated polymers, 1,3-dioxolane derivatives and the like aredisclosed in U.S. Pat. No. 3,308,107, U.S. Pat. No. 3,450,716; IzvestiyaA Kademii Nank SSSR, Seriya Khimicheskaya. pp. 392-395, February 1988 byV. S. Yuminov et al. and pp/938-, April 1989 by V. S. Yuminov et al; andthe like.

However, 1,3-dioxolane derivatives that have been conventionally knownare limited to the structures of a compound represented by the followingformula (A) disclosed in U.S. Pat. No. 3,978,030, a compound representedby the following formula (B) disclosed in JP-A No. 5-339255, and thelike. In these compounds, only a specific substitutional group can belocated at a specified site on a five-membered ring of dioxolane.

In Formula (B), R_(f) ^(1′) and R_(f) ^(2′) each independently representa polyfluoroalkyl group having 1 to 7 carbon atoms.

Such structural limitation results from the synthetic processes employedto form the polymers. For example, in a conventional method forsynthesis of the compound represented by the above formula (A), only onefluorine-containing group may be located on a 1,3-dioxolane ring, andthe fluorine-containing group that can be introduced is limited to atrifluoroalkyl group. In a conventional method for synthesis of thecompound represented by the above formula (B), one polyfluoroalkyl groupthat can be introduced into a 1,3-dioxolane ring is located at each siteof 4- and 5-membered rings, that is, the number of polyfluoroalkyl groupis inevitably limited to two in total. Further, a material used forsynthesizing the fluorinated compound represented by formula (B) is acompound represented by the following formula (C), and it is difficultto synthesize such compound.

SUMMARY OF THE INVENTION

The present inventors have developed the following synthetic methods,therefrom have derived useful and novel fluorinated compounds, andoptical or electrical materials using the polymers. The presentinvention will be described below.

A first aspect of the present invention is a method for producing afluorinated compound represented by the following formula (3), themethod comprising a step of fluorinating, in a fluorine-based solutionunder a fluorine gas atmosphere, a compound obtained by reacting atleast one of kind of compound represented by the following formula (1)and at least one kind of compound represented by the following formula(2):

wherein in formula (1), X represents a hydrogen atom or a fluorine atom,and Y represents an alkyl group having 1 to 7 carbon atoms or apolyfluoroalkyl group having 1 to 7 carbon atoms; and in formula (2), Zrepresents a hydroxyl group, a chlorine atom, or a bromine atom, and R¹to R⁴ each independently represent a hydrogen atom, an alkyl grouphaving 1 to 7 carbon atoms or a polyfluoroalkyl group having 1 to 7carbon atoms.

wherein, in formula (3), R_(ff) ¹ to R_(ff) ⁴ each independentlyrepresent a fluorine atom or a perfluoroalkyl group having 1 to 7 carbonatoms.

A second aspect of the present invention is the method for producing afluorinated compounds according to the first aspect, wherein thefluorine gas atmosphere is a mixed atmosphere of nitrogen gas andfluorine gas, and a proportion of the nitrogen gas with respect to thefluorine gas is in a range from 2 to 4.

A third aspect of the present invention is the method for producing afluorinated compounds according to the first aspect, wherein, in thestep of fluorinating, a reaction temperature is kept in a range of 0 to5° C., and stirring is carried out.

A fourth aspect of the present invention is a fluorinated compoundrepresented by the following formula (4):

wherein, in formula (4), R_(ff) ¹ and R_(ff) ² each independentlyrepresent a fluorine atom or a perfluoroalkyl group having 1 to 7 carbonatoms, and n represents an integer from 1 to 4.

A fifth aspect of the present invention is a fluorinated polymerobtained by polymerization of the fluorinated compound according to thefourth aspect.

A sixth aspect of the present invention is an optical or electricalmaterial comprising the fluorinated polymer according to the fifthaspect.

A seventh aspect of the present invention is an optical or electricalmaterial according to the sixth aspect, wherein the optical material isan optical wave guide, an optical lens, a prisms, a photo mask, or anoptical fiber.

A eighth aspect of the present invention is a compound represented bythe following formula (5):

wherein, in formula (5) X represents a hydrogen atom or a fluorine atom,Y represents a hydrogen atom, an alkyl group having 1 to 7 carbon atoms,or a polyfluoroalkyl group having 1 to 7 carbon atoms, and R¹ to R⁴ eachindependently represent a hydrogen atom, an alkyl group having 1 to 7carbon atoms, or a polyfluoroalkyl group having 1 to 7 carbon atoms.

A ninth aspect of the present invention is a compound represented by thefollowing formula (6):

wherein, in formula (6), X represents a hydrogen atom or a fluorineatom, Y represents a hydrogen atom, an alkyl group having 1 to 7 carbonatoms, or a polyfluoroalkyl group having 1 to 7 carbon atoms, R³ or R⁴each independently represent a hydrogen atom, an alkyl group having 1 to7 carbon atoms, or a polyfluoroalkyl group having 1 to 7 carbon atoms,and n represents an integer from 1 to 4.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a graph showing refractive indexes of polymers synthesized byExamples 2 and 4.

FIG. 2 is a graph showing the material dispersion of the polymersynthesized by Example 2.

FIG. 3 is a graph showing the optical transmission of the polymersynthesized by Example 4.

DESCRIPTION OF SPECIFIC EMBODIMENTS

1. Method for Producing Fluorinated Compounds

A description will be given of a method for producing fluorinatedcompounds, that are 1,3-dioxolane derivatives, according to the presentinvention.

In the production method of the present invention, a fluorinatedcompound that uses 1,3-dioxolane derivatives, represented by thefollowing formula (3), is produced using the following formulae (1) and(2) in a fluorine-based solution in a flow of fluorine gas.

In Formula (1), X represents a hydrogen atom or a fluorine atom. Fromthe viewpoint of ready availability, X is preferably a hydrogen atom. Yrepresents an alkyl group having 1 to 7 carbon atoms, preferably 1 to 3carbon atoms, or a polyfluoroalkyl group having 1 to 7 carbon atoms,preferably 1 to 3 carbon atoms, more preferably a perfluoroalkyl grouphaving 1 to 3 carbon atoms. Specially preferably, Y represents an alkylgroup having 1 to 3 carbon atoms

In Formula (2), Z represents a hydroxyl group, chlorine atom, or bromineatom.

In Formula (2), R¹ to R⁴ each independently represent a hydrogen atom,an alkyl group having 1 to 7 carbon atoms, or an polyfluoroalkyl grouphaving 1 to 7 carbon atoms. After the compound represented by Formula(1) and the compound represented by Formula (2) are made to react witheach other, hydrogen atoms that form a product are all fluorinated.Therefore R¹ to R⁴ may be hydrogen atom, alkyl group, or polyfluoroalkylgroup. More preferably, R¹ to R⁴ each independently represent a hydrogenatom, or an alkyl group having 1 to 7 carbon atom because ofcost-effective. Specifically preferably, R¹ to R⁴ each independentlyrepresent a hydrogen atom, or an alkyl group having 1 to 3 carbon atom.R¹ and R² may be bonded to each other to form a ring.

In Formula (3), R_(ff) ¹ to R_(ff) ⁴ each independently represent afluorine atom, or a perfluoroalkyl group having 1 to 7 carbon atoms.Preferably, R_(ff) ¹ to R_(ff) ⁴ each independently represent a fluorineatom, or a perfluoroalkyl group having 1 to 3 carbon atoms. R_(ff) ¹ andR_(ff) ⁴ may be bonded to each other to form a ring.

Reaction schemes of these compounds are exemplified below, but thepresent invention is not limited to the same.

The production process of the present nvention is broadly divided into,preferably, at least four steps as below.

(1) a step in which the compound represented by the above formula (1)and the compound represented by the above formula (2) are made toundergo dehydration or dehydro halogenation reaction;

(2) a step in which the above compounds are fluorinated in afluorine-based solution;

(3) a step in which a carboxylate salt is produced by a base; and

(4) a step of heating in order to decarboxylate the obtained carboxylatesalt.

These four steps (1) to (4) will be described below in detail.

Step (1):

It is preferable that the compound represented by Formula (1) and thecompound represented by Formula (2) are made to react with each other atan equimolar ratio. The compounds represented by Formula (1) may be usedeither singly or in combination of two or more. Further, the compoundsrepresented by Formula (2) may be used either singly or in combinationof two or more.

Moreover, since the above is an exothermic reaction, these compounds arepreferably made to react with each other while being cooled. Otherreaction conditions are not particularly limited, and prior to thesubsequent step (2), a purification process such as distillation is alsopreferably added.

Step (2):

In this step, hydrogen atoms of the compound prepared by the step (1)are all substituted with fluorine atoms. To that end, preferably, thehydrogen atoms are directly fluorinated in a fluorine-based solution. Asfor such direct fluorination, refer to Synthetic Fluorine Chemistry, Edsby G. A. Olah, R. D. Chambers, and G. K. S. Prakash, J. Wiley and Sons.Inc. New York (1992), by R. J. Lagow, T. R. Bierschenk, T. J. Juhlke andH. kawa, Chapter 5: Polyether Synthetic Method.

The fluorine-based solution is not particularly limited. For example,1,1,2-trichlorotrifluoroethane, polyfluorobenzene, and the like arepreferable. Specific examples thereof include Fluorinert FC-75, FC-77,FC-88 (produced by 3M Corporation), and the like. The ratio offluorine-based solution to the compound prepared by the step (1) is 2-10times (mass ratio), more preferably, the ratio is 3-4 times.

The fluorination is carried with fluorine gas diluted with nitrogen gas.The ratio of nitrogen gas to fluorine gas is preferably 2-6 times(volume ratio), more preferably, the ratio is 2-4 times larger thanfluorine gas.

The compound obtained through the step (1) is dissolved in thefluorine-based solvent (the weight ratio of the compound to the solutionis 0.40-0.50). The solution is added slowly into the fluorine-basedsolution under F₂/N₂ stream. The addition rate is preferably 0.3 ml/min.to 20 ml/min., more preferably 0.5 ml/min. to 10 ml/min.

The reaction of the step (2) is carried out by controlling temperature.The reaction temperature should be under 5° C., preferably at between 0°C. and 5° C. During step (2), the solution is preferably well stirred.

Step (3):

A carboxylate salt is produced from the fluorine compound obtained bystep (2) by a base. As the base, potassium hydroxide, sodium hydroxide,cesium hydroxide, and the like are preferable. Potassium hydroxide ismore preferable.

Step (4):

The obtained carboxylate salt is heated and decarboxylated. The heatingtemperature is preferably in the range of 250° C. to 320° C., and morepreferably in the range of 270° C. to 290° C.

In the production method of the present invention, other steps inaddition to the above steps (1) to (4) can be added.

2. Method for Producing Fluorinated Polymers

The above fluorinated compound undergoes radical polymerization inaccordance with an ordinary method, thereby allowing production of afluorinated polymer. A peroxide is preferably used as a radicalcatalyst, but in order that a fluorine atom of the fluorine compound maynot be substituted with a hydrogen atom, a perfluoroperoxide is used.

3. Fluorinated Compound

In the production method of the present invention, a hydrogen atom canbe substituted with a perfluoro group or a fluorine atom at an arbitrarysite on a 1,3-dioxolane ring, and perfluoro-2-methylene-1,3-dioxolanerepresented by the following formula (3) can be obtained.

In Formula (3), R_(ff) ¹) to R_(ff) ⁴ each independently represent afluorine atom, or a perfluoroalkyl group having 1 to 7 carbon atoms.Preferably, R_(ff) ¹) to R_(ff) ⁴ each independently represent afluorine atom, or a perfluoroalkyl group having 1 to 3 carbon atoms.

The compound represented by Formula (3) can be easily polymerized usinga peroxide. Further, this compound has a five-membered ring and is astable material. In the case of a six-membered ring, ring-opening isliable to occur at the time of polymerization, and therefore, aresulting polymer becomes a mixture. In this case, physical propertiessuch as heat resistance are liable to deteriorate.

Further, a compound represented by the following formulae (4) is a novelcompound.

R_(ff) ¹ and R_(ff) ² each independently represent a fluorine atom, or aperfluoroalkyl group having 1 to 7 carbon atoms, and n represents aninteger of 1 to 4, preferably, an integer of 1 to 2.

4. Method for Producing Fluorinated Polymers

The above fluorinated compound undergoes radical polymerization inaccordance with an ordinary method, thereby allowing production of afluorinated polymer. A peroxide is preferably used as a radicalcatalyst, but in order that a fluorine atom of the fluorine compound maynot be substituted with a hydrogen atom, a perfluoroperoxide is used.

5. Application of Fluorinated Polymer

A polymer obtained by polymerization of the compound represented byFormula (4) can be suitably used for optical or electrical materials.This polymer has a high glass transition temperature and it is amorphousmaterial. Therefore, such polymer can be suitably used for plasticoptical fibers, light wave guides, optical lenses, prisms, photo masks,and the like, more suitably used for plastic optical fibers, light waveguides material, optical lenses.

Example 1 Synthesis of perfluoro-4-methyl-2-methylene-1,3-dioxolanePreparation of 2-carbomethyl-2-trifluoromethyl-4-methyl-1,3-dioxolane

A 3 L 3-necked flask equipped with a water-cooled condenser, athermometer, a magnetic stirrer and a pressure-equalizing droppingfunnel were made usable. The flask was charged with 139.4 g (1.4 mol) ofa mixture of 2-chloro-1-propanol and 1-chloro-2-propanol. The flask wascooled to 0° C. and methyl trifluoropyruvate was slowly added thereto.After addition, the reaction mixture was stirred for additional 2 hours.Then 100 ml of DMSO and 194 g of potassium carbonate were further addedduring one hour. Stirring was continued for another 8 hours, therebyobtaining a reaction mixture. The reaction mixture obtained was pouredinto 1 L of water. Dichloromethylene extracts were combined with theorganic phase. Subsequently, the reaction mixture was dried withmagnesium sulfate. After removing the solvent, 245.5 g of crude productwas obtained. The crude product was fractionally distilled at reducedpressure (12 Torr), and 230.9 g of pure product of2-carbomethyl-2-trifluoromethyl-4-methyl-1,3-dioxolane was obtained. Theboiling point of the pure product was 77 to 78° C., and the yield was77%.

HNMR (ppm): 4.2 to 4.6, 3.8 to 3.6 (CHCH₂, multiplet, 3H), 3.85 to 3.88(COOCH₃, multiplet, 3H), 1.36 to 1.43 (CCH₃, multiplet, 3H);

¹⁹FNMR (ppm): −81.3 (CF3, s, 3F).

Fluorination of 2-carbomethyl-2-trifluoromethyl-4-methyl-1,3-dioxolane

A 10 L stirring-reactor vessel was loaded with 4 liters of1,1,2-trichlorotrifluoroethane. The nitrogen flow was set at 1340 cc/minand the fluorine flow was out at 580 cc/min, thereby making the interiorof the stirring-reactor vessel under a nitrogen/fluorine atmosphere.After 5 minutes, 290 g of the prepared2-carbomethyl-2-trifluoromethyl-4-methyl-1,3-dioxolane was dissolved to750 ml of 1,1,2-trichloro-trifluoroethane solution, and then thissolution was added into the reactor at a rate of 0.5 ml/min. The reactorvessel was cooled to 0° C. After all the dioxolane was added over 24hours, the fluorine flow was stopped. After purging with nitrogen gas,an aqueous KOH solution was added to the reactor until it turned toslight alkali.

After removing volatile materials under reduced pressure. The residuewas further dried under reduced pressure at 70° C. for 48 hours, therebyobtaining a solid reaction product. The solid reaction product wasdissolved in 500 ml of water and excess of hydrochloric acid was addedto obtain two phases, that is, an organic phase and a water phase. Theorganic layer was separated and distilled under reduced pressure. As aresult, perfluoro-2,4-dimethyl-1,3-dioxolane-2-carboxylic acid wasproduced. The boiling point of the main distillate was 103 to 106°C./100 mmHg. The overall fluorination yield was 85%.

Synthesis of perfluoro-4-methyl-2-methylene-1,3-dioxolane

Perfluoro-2,4-dimethyl-2-potassium carboxylate-1,3-dioxolane wasobtained by neutralization of the above distillate with an aqueous KOHsolution. The potassium salt was dried at 70° C. under vacuum for oneday. The salt was decomposed with a stream of nitrogen or argonatmosphere at 250 to 280° C. to yield the product which was collected ina trap cooled to −78° C., thereby obtainingperfluoro-4-methyl-2-methylene-1,3-dioxolane (yield: 82%). The producthad the boiling point of 45° C./760 mmHg, and was identified using¹⁹FNMR and GC-MS as below.

¹⁹FNMR: −84 ppm (3F, CF₃), −129 ppm (2F, ═CF₂);

GC-MS: m/e 244 (Molecular ion) 225, 197, 169, 150, 131, 100, 75, 50.

Synthetic schemes according to Example 1 are schematically shown below.

Example 2 Polymerization of perfluoro-4-methyl-2-methylene-1,3-dioxolane

100 g of perfluro-4-methyl-2-methylene-1,3-dioxolane and 1 g ofperfluorobenzoyl peroxide were charged in a glass tube, which was thendegassed and refilled with argon in two vacuum freeze-thaw cycles. Thetube was sealed and heated at 50° C. for several hours. The contentbecame solid. Further the tube was kept to be heated at 70° C. overnight and 100 g of a transparent bar was obtained.

The transparent bar was dissolved in Fluorinert FC-75 (produced by 3MCorporation) and a thin film of polymer was obtained by casting thesolution on a glass plate. The glass transition temperature of thepolymer was 117° C. The polymer was completely amorphous. Thetransparent bar was purified by precipitation from the hexafluorobenzenesolution by adding chloroform thereto. The glass transition temperatureof the product was increased to 133° C.

The refractive indexes at various wavelengths were shown by the line ofA in FIG. 1, and the material dispersion of the polymer was shown inFIG. 2. It can be seen from such refractive indexes that the obtainedpolymer is suitable for optical fibers, optical waveguides, and photomasks.

Example 3 Synthesis of perfluoro-4,5-dimethyl-2-methylene-1,3-dioxolaneSynthesis of 2,4,5-trimethyl-2-carboxymethyl-1,3-dioxolane

A reaction mixture: 2.0 mol of 2,3-butanediol, 2.0 mol of methylpyruvate, 10 g of a cation exchange resin (H form), and 1 L of absolutebenzene were refluxed until no more water came to be produced in a flaskfitted with a Dean-Stark trap, thereby obtaining2,4,5-trimethyl-2-carboxymethyl-1,3-dioxolane. The yield was 75% and theboiling point of the product was 45° C./1.0 mmHg.

¹HNMR: 1.3 ppm (6H, —CH₃), 1.56 ppm (3H, —CH₃), 3.77 ppm (3H, OCH₃), 3.5to 4.4 ppm (m, 2H, —OCH—).

Synthesis of perfluoro-2,4,5-trimethyl-2-carboxylic acid-1,3-dioxolane

500 g of the obtained 2,4,5-trimethyl-2-carboxymethyl-1,3-dioxolane wasfluorinated with fluorine gas diluted with nitrogen in Fluorinert FC-75(trade name) as described in Example 1. After completion of thereaction, nitrogen gas was purged for 30 minutes. The obtained mixturewas then treated with an aqueous KOH solution to form an organic phaseand a slightly-alkaline water phase. The water of the water phase wasremoved under reduced pressure, and a solid material was therebyobtained. The solid material obtained was acidified with concentratedhydrochloric acid and distilled out, thereby obtainingperfluoro-2,4,5-trimethyl-2-carboxylic acid-1,3-dioxolane. The yield was85%, and the boiling point was 61° C./2.5 mmHg.

Synthesis of perfluoro-4,5-dimethyl-2-methylene-1,3-dioxolane

Perfluoro-2,4,5-trimethyl-2-potassium carboxylate-1,3-dioxolane wasobtained by neutralization of the above distillate with an aqueous KOHsolution. The obtained potassium salt was dried at 70° C. under vacuumfor one day. The salt was further decomposed with stream of nitrogen orargon at 250 to 280° C. to yield the product which was collected in atrap cooled to −78° C. As a result,perfluoro-4,5-dimethyl-2-methylene-1,3-dioxolane was obtained (yield:78%). The boiling point of the product was 60° C. The product wasidentified using ¹⁹FNMR and GC-MS.

¹⁹FNMR: −80 ppm (6F, —CF₃), −129 ppm (2F, ═CF₂);

GC-MS: m/e 294 (Molecular ion).

Synthetic schemes according to Example 2 are schematically shown below.

Example 4 Polymerization ofperfluoro-4,5-dimethyl-2-methylene-1,3-dioxolane

10 g of the perfluoro-4,5-dimethyl-2-methylene-1,3-dioxolane obtained byExample 3 and 80 mg of perfluorobenzoylperoxide were charged in a glasstube, which was then degassed and refilled with argon in three vacuumfreeze-thaw cycles. The tube was sealed and heated at 50° C. for oneday. The content became solid and the tube was kept to be heated at 70°C. for 4 days. 10 g of a transparent bar was obtained.

The transparent bar was purified by dissolving a part thereof in ahexafluorobenzene solution and also by precipitation from ahexafluorobenzene solution with chloroform being added thereto. Theyield was 98% or greater. Solution polymerization of the monomer wasperformed in Fluorinert FC-75 (trade name) using perfluorobenzoylperoxide as an initiator.

¹⁹FNMR of the obtained polymer was −80 ppm (6F, —CF₃), −100 to −120 ppm(2F, main chain) and −124 ppm (2F, —OCF). The refractive indexes of theobtained polymer are shown by the line B in FIG. 1, and the opticaltransmission thereof in the range of 200 to 2000 nm is shown in FIG. 3.It can be seen from such refractive indexes and optical transmissionthat the obtained polymer is suitable for optical fibers, optical waveguides, and photo masks.

Example 5 Synthesis ofperfluoro-4,5-cyclotetramethylene-2-methylene-1,3-dioxolane Synthesis of2-methyl-2-methoxycarboxyl-4,5-cyclotetramethylene-1,3-dioxolane

A reaction mixture: 100 g (1 mol) of 1,2-cyclohexanediol, 204 g (2 mols)of methyl pyruvate, 1.5 L of absolute benzene, and 10 g of a cationexchange resin (H form) was refluxed until no more water came to beproduced in a flask fitted with a Dean-Stark trap. The cation exchangeresin was removed by filtration. The product was distilled at 65° C./5mmHg, thereby obtaining2-methyl-2-methoxycarboxyl-4,5-cyclotetramethylene-1,3-dioxolane. Theyield was 50 to 60%.

Fluorination of2-methyl-2-methoxycarboxyl-4,5-cyclotetramethylene-1.3-dioxolane

The obtained2-methyl-2-methoxycarboxyl-4,5-cyclotetramethylene-1,3-dioxolane wasfluorinated in a fluorinated solvent, Fluorinert FC-75 (trade name) withF₂/N₂ as described in Example 1. After completion of the reaction, byremoving the solvent and produced hydrogen fluoride, and then treatingthe fluorinated product with an aqueous KOH solution,perfluoro-2-methyl-2-potassiumcarboxylate-4,5-cyclotetramethylene-1,3-dioxolane was obtained. Theobtained potassium salt was dried by heating at 60° C. under reducedpressure (yield: 75%) and the dried potassium salt was decomposed at250° C. in the nitrogen gas atmosphere. The product;perfluoro-4,5-cyclotetramethylene-2-methylene-1,3-dioxolane wascollected in a trap cooled to −78° C. and the yield thereof was 85%. Theboiling point of the product was 60° C. The product was identified using¹⁹FNMR and GC-MS.

¹⁹FNMR: −137 ppm (2F, ═CF₂), 126 to 134 ppm (8F, CF₂), −125 ppm (2F,OCF);

GC-MS: m/e 360 (Molecular ion).

Synthetic schemes according to Example 5 are schematically shown below.

Example 6 Polymerization ofperfluoro-4,5-cyclotetramethylene-2-methylene-1,3-dioxolane

10 g of the perfluoro-4,5-cyclotetramethylene-2-methylene-1,3-dioxolaneobtained by Example 5 and 80 mg of perfluorobenzoyl peroxide werecharged in a glass tube, which was then degassed and refilled with argonin two vacuum freeze-thaw cycles. The tube was sealed and heated at 50°C. for 12 hours. The content of tube became solid and the tube was keptto be heated at 70° C. over night. 10 g of a transparent rod wasobtained.

The resulting polymer was completely amorphous and transparent. Therefractive indexes of the polymer were 1.3160 (632.8 nm) and 1.3100(1544 nm), and the glass transition temperature thereof was about 160°C.

¹⁹FNMR: −120 to −140 ppm (8F, CF₂), −100 to −118 ppm (2F, main chain),and 120 ppm (2F, −OCF). It can be seen from the viewpoint of a highglass transition temperature that the obtained polymer is less subjectto heat deformation, and is suitable for electrical materials, opticalfibers, optical wave guides, and the like.

Example 7 Synthesis ofperfluoro-4,5-cyclotrimethylene-2-methylene-1,3-dioxolane Synthesis of2-methyl-2-methoxycarboxyl-4,5-cyclotrimethylene-1,3-dioxolane

A reaction mixture: 102 g (1 mol) of 1,2-cyclopentanediol, 204 g (2mols) of methyl pyruvate, 1.5 L of absolute benzene, and 10 g of acation exchange resin (H form) was refluxed until no more than watercame to be produced. After the cation exchange resin was removed byfiltration, the product was distilled at 67° C./20 mmHg, therebyobtaining2-methyl-2-methoxycarboxyl-4,5-cyclotrimethylene-1,3-dioxolane. Theyield was 60 to 70%.

55

Fluorination of2-methyl-2-methoxycarboxyl-4,5-cyclotrimethylene-1,3-dioxolane:

The obtained2-methyl-2-methoxycarboxyl-4,5-cyclotrimethylene-1,3-dioxolane wasfluorinated in a fluorinated solvent, Fluorinert FC-75 (trade name) withF₂/N₂ as described in Example 1. The reaction product was treated withpotassium hydroxide to thereby produce perfluoro-2-methyl-2-potassiumcarboxylate-4,5-cyclotrimethylene-1,3-dioxolane. The potassium saltobtained was dried by heating at 60° C. under reduced pressure. Theyield was 82%. The dried potassium salt was decomposed at 260° C. in theflow of argon gas. The crude product was distilled at 85° C. to produceperfluoro-4,5-cyclotrimethylene-2-methylene-1,3-dioxolane (yield: 79%).

Synthetic schemes according to Example 7 are schematically shown below.

Example 8 Polymerization ofperfluoro-4,5-cyclotrimethylene-2-methylene-1,3-dioxolane

20 g of the perfluoro-4,5-cyclotrimethylene-2-methylene-1,3-dioxolaneobtained by Example 5 and 150 mg of perfluorobenzoyl peroxide werecharged in a glass tube. The polymerization was carried out as describedin Example 2. A transparent amorphous polymer was obtained. The glasstransition temperature of the polymer was found to be 150° C.

As described above, the polymers obtained are highly transparent andamorphous and also have a high glass transition temperature, andtherefore, they are found as excellent materials that can be used forvarious applications of optical fibers, electrical materials, and thelike.

1-3. (canceled)
 4. A fluorinated compound represented by the following formula (4):

wherein R_(ff) ¹ and R_(ff) ² each independently represents a fluorine atom or a perfluoroalkyl group having 1 to 7 carbon atoms, and n represents an integer from 1 to
 4. 5. A fluorinated polymer obtained by polymerization of the fluorinated compound according to claim
 4. 6. An optical or electrical material comprising the fluorinated polymer according to claim
 5. 7. An optical or electrical material according to claim 6, wherein the optical material is optical wave guides, an optical lens, a prisms, a photo masks, or an optical fiber.
 8. A compound represented by the following formula (5):

wherein X represents a hydrogen atom or a fluorine atom, Y represents a hydrogen atom, an alkyl group having 1 to 7 carbon atoms, or a polyfluoroalkyl group having 1 to 7 carbon atoms, and R¹ to R⁴ each independently represents a hydrogen atom, an alkyl group having 1 to 7 carbon atoms, or a polyfluoroalkyl group having 1 to 7 carbon atoms.
 9. A compound represented by the following formula (6):

wherein X represents a hydrogen atom or a fluorine atom, Y represents a hydrogen atom, an alkyl group having 1 to 7 carbon atoms, or a polyfluoroalkyl group having 1 to 7 carbon atoms, R³ or R⁴ each independently represents a hydrogen atom, an alkyl group having 1 to 7 carbon atoms or a polyfluoroalkyl group having 1 to 7 carbon atoms, and n represents an integer from 1 to
 4. 